/*
 Navicat Premium Data Transfer

 Source Server         : 106.54.193.225
 Source Server Type    : MySQL
 Source Server Version : 50736
 Source Host           : 106.54.193.225:3306
 Source Schema         : day02rk

 Target Server Type    : MySQL
 Target Server Version : 50736
 File Encoding         : 65001

 Date: 19/07/2024 09:07:19
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for t_course
-- ----------------------------
DROP TABLE IF EXISTS `t_course`;
CREATE TABLE `t_course`  (
  `course_id` int(11) NOT NULL AUTO_INCREMENT,
  `course_name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`course_id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_course
-- ----------------------------
INSERT INTO `t_course` VALUES (1, '语文');
INSERT INTO `t_course` VALUES (2, '数学');
INSERT INTO `t_course` VALUES (3, '英语');

-- ----------------------------
-- Table structure for t_scope
-- ----------------------------
DROP TABLE IF EXISTS `t_scope`;
CREATE TABLE `t_scope`  (
  `scope_id` int(11) NOT NULL AUTO_INCREMENT,
  `course_id` int(11) NULL DEFAULT NULL,
  `student_id` int(11) NULL DEFAULT NULL,
  PRIMARY KEY (`scope_id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 11 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_scope
-- ----------------------------
INSERT INTO `t_scope` VALUES (1, 1, 1);
INSERT INTO `t_scope` VALUES (2, 1, 2);
INSERT INTO `t_scope` VALUES (3, 1, 3);
INSERT INTO `t_scope` VALUES (4, 2, 3);
INSERT INTO `t_scope` VALUES (5, 2, 4);
INSERT INTO `t_scope` VALUES (6, 2, 5);
INSERT INTO `t_scope` VALUES (7, 3, 6);
INSERT INTO `t_scope` VALUES (8, 3, 7);
INSERT INTO `t_scope` VALUES (9, 3, 8);
INSERT INTO `t_scope` VALUES (10, 3, 9);

-- ----------------------------
-- Table structure for t_student
-- ----------------------------
DROP TABLE IF EXISTS `t_student`;
CREATE TABLE `t_student`  (
  `student_id` int(11) NOT NULL AUTO_INCREMENT,
  `student_name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  `student_sex` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`student_id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 99 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of t_student
-- ----------------------------
INSERT INTO `t_student` VALUES (1, '张三', '男');
INSERT INTO `t_student` VALUES (2, 'CVBS', '女');
INSERT INTO `t_student` VALUES (3, '理论', '女');
INSERT INTO `t_student` VALUES (4, '解决', '男');
INSERT INTO `t_student` VALUES (5, '慢慢', '男');
INSERT INTO `t_student` VALUES (6, '利旧', '女');
INSERT INTO `t_student` VALUES (7, '赵六', '男');
INSERT INTO `t_student` VALUES (8, '田七', '男');
INSERT INTO `t_student` VALUES (9, '李四', '女');
INSERT INTO `t_student` VALUES (10, '王五', '男');

SET FOREIGN_KEY_CHECKS = 1;




SELECT count(student_sex),student_sex count FROM t_student GROUP BY student_sex



-- 3.查询男生和女生各多少人。（15分）
SELECT count(student_sex) count,student_sex  FROM t_student GROUP BY student_sex

-- 4.	查询男生和女生分别占总人数的比例。（20分）
SELECT count(student_id) count FROM t_student WHERE COUNT(student_sex) GROUP BY student_sex


-- 5.查询每门课程下的学生总人数。（15分）

SELECT
    count(*),c.course_name
FROM
    t_scope s
        LEFT JOIN t_course c ON s.course_id = c.course_id
        LEFT JOIN t_student t ON t.student_id = s.student_id
GROUP BY c.course_id






















